Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

In a presentation late last week to American Psychological Association, two nationally representative surveys totaling nearly 5,000 pre-teens and teens found that 15 percent said they’d been bullied on the Internet during the past year. (Updated: An earlier version of this story reported a cyberbullying rate of 17 percent. Based on a new analysis, Ybarra revised the estimate to 15 percent.) While that at first may seem high, past studies had pegged the cyberbullying victim rateanywhere from 30 percent to as lofty as 72 percent.

“We assume it’s this overwhelming thing, that everybody’s being bullied and that it’s inescapable -- that’s not totally accurate,” says Michele Ybarra, research director at the nonprofit Center for Innovative Public Health Research in San Clemente, Calif.

Her analysis of the two surveysconducted by Harris Interactive of randomly selected, anonymous adolescents was focused on debunking assumptions of how young people are using the Internet and their experiences online. High-profile cases of youth suicides blamed on cyberbullying -- such as Tyler Clementi, the Rutgers University student who committed suicide after his roommate used a webcam to spy on his encounter with another man, or 15-year-old Phoebe Prince from western Massachusetts who took her own life after being targeted by hateful online messages --have helped fuel the impression that cyberbullying affects most young people.

“Because we’re seeing stories that are really serious,” Ybarra says, “it does give this sort of sense that it is happening all over the place.”

“What she tries to do is look at the bullying definition and see if it applies to cyberbullying,” says Haber, a clinical psychologist and authorbased in White Plains, N.Y., who has reviewed Ybarra’s research.

Indeed, there’s debate over what cyberbullying actually is. Traditional bullying involves repetitive episodes of abuse carried out by one person who is viewed to have more power, usually physical, over the victim. Ybarra has simply applied that narrow definition to cyberbullying to hone the statistics. But in the online world, power is also judged by status and digital popularity, such as having a higher number of Facebook friends.

“She’s trying to get to the bottom of the cyberbullying problem, which I have to give her credit for,” Haber says.

One reason for the lower-than-expected number could be that Ybarra, unlike other researchers, purposely omits cyber-harassment from her definition of cyberbullying. Unlike cyberbullying, online harassment is defined more as a one-time event. Haber agrees with that approach.

“Whether it’s kids being exclusionary online or being mean online, harassment happens more frequently than real cyberbullying, where somebody has more power over you and hurts you,” Haber says. “We can’t lump in all this stuff together.”

In the new study, as many as 41 percent of adolescents reported experiencing cyber-harassment, meaning those cases were more isolated or that the mean-spirited verbiage was sent by someone who didn’t hold any inherent power over the recipient.

Despite the new research, New Jersey mom Victoria Marin believes the 15 percent finding is lower than the true rate.

Her 10-year-old son was the target of a swarm of stinging texts after the fifth-grader with dyslexia mistakenly typed “hay” instead of “hey.”

“You are an idiot who shouldn’t have a cell phone,” read one message. “You are a retard who shouldn’t text anymore,” read another.

The “cyber campaign,” as his mother calls it, dragged on secretly for two months last fall, a private bullying war waged by other boys against an increasingly withdrawn victim. As the text assaults looped in more students, he was shunned from kickball games and lunch gatherings. Soon, his grades plummeted, headaches emerged, and he stopped talking. That's when his mother Victoria investigated her son's phone and discovered a blitz of vicious, undeleted messages.

The New Jersey mom immediately blocked the bullies, withdrew her so from classes and began home-schooling him.

“He’s afraid to go back,” his mother says.. “I would be putting him back into the same school, with the same kids.”

Victoria is convinced, "there more kids out there – like my son – who are not reporting it, even in a survey."

She continues. “How many of those kids are really telling what’s going on, or are they too afraid to report it? My son begged me: ‘Please don’t tell the teacher, don’t tell the school,’ because they always fear retaliation either from the school, the teacher or the bullies.

“Had I not gone through my son’s phone, I would have never known and it would have continued,” she adds. “And I would have just thought he was a quiet kid who didn’t want to go to school.”

Spotting, identifying and stopping true cyber-bullying is trickier than breaking up a playground fight between a bully and a victim, Haber said, because many online jabs lack tone and context. In other words, a remark from one teen to another that may be meant as sarcastic yet good-natured teasing may be misconstrued as harassment or as true bullying by some adolescents.

"Lots of kids report that other kids say mean or hurtful things online or that they purposely leave them out of group things online," Haber said. "But because they don’t have the context, they don’t know if it was intentional .... But one of the kids could still feel bad, could still believe they were being harassed," or even perhaps feel they were being bullied.

"Straight cyberbullying happens over time, and it's about power," Haber said.